Croscarmellose sodium has been widely used as a dispersant and disintegrant in the pharmaceutical industry. It is known to have been used as a "super disintegrant" for pharmaceutical tablets where rapid disintegration and/or dispersion is required to render pharmaceutical actives promptly physiologically available. Croscarmellose is typically used in such applications in combination with other pharmaceutically acceptable adjuvants such as binders, lubricants, dispersants, surface active agents and the like, all of which are well known to those skilled in the art of formulating pharmaceutically active agents.
Bitter tasting pharmaceutically active agents are particularly difficult to render palatable when placed in tableted dosage forms. Much research and many techniques have been employed in the art to effectively mask the taste of bitter tasting pharmaceuticals without retarding the physiological availability of the bitter tasting active ingredients. Well known methods for taste masking generally have involved coating of the particles of the active ingredient and/or the tablet containing such active ingredient, with various coating materials or combinations of coating materials many or most of which have limited water solubility and are therefore applied from organic media. However, on the one hand, the more water soluble such coatings are, the less effective they are in taste masking, and on the other hand the less water soluble they are the more they tend to retard the physiological availability of the active ingredient. Moreover, in order to achieve both rapid disintegration and taste masking it has been necessary to use both a coating and a disintegrant or super disintegrant, such as croscarmellose sodium, in the tablet formulation. This is extremely costly in requiring both a coating step and the addition of relatively costly disintegrants. Accordingly there is a continuing need for less costly and more effective methods for achieving taste masking while at the same time assuring prompt physiological availability of the active ingredient. It is a further advantage of the present invention that the coating solution employed herein is entirely aqueous, so that there is no organic residue left in the coated particles.
It has now been found that these and other objects of the invention can be achieved by utilizing croscarmellose sodium as both a coating agent and as a disintegrant, thereby eliminating the need for use of separate coating and disintegrants in tableting formulations. It has further been found that particle size of the active ingredient and the method used to coat the active both play an important role in the ability to use croscarmellose sodium to serve both functions. These findings are particularly surprising and unexpected in view of the fact that croscarmellose sodium has not heretofore been used as a taste masking agent.